This invention relates to apparatus for loading vehicles with assembled logs or other elongate loads and more particularly to such an apparatus that can be carried to the loading site by the vehicle to be loaded.
Traditionally, logs gathered at a forest loading site have been loaded onto logging trucks by a heavy-duty log loader equipped with a grapple. As each truck arrives at the site, the loader drops a load of logs onto the truck bed. Since each log truck must be loaded by the single loader, considerable time is lost when several trucks are waiting to be loaded. Consequently, the log loader is often inactive when no trucks are present for loading.
This drawback of the traditional loading system was largely met by the loading apparatus I disclosed in U.S. Pat. No. 3,549,027. That apparatus, simple and inexpensive, comprises a rectangular frame with several pairs of extensible columns for retaining and raising a load of logs. The logging truck can then back beneath the load of logs, which is lowered onto the truck bed. A truck can tow such apparatus behind it to the loading site so that no loading bottleneck is created. Moreover, because of its design, the apparatus does not require a specialized log loader but can be loaded by a bulldozer, rubber-tired skidder, or other tractor vehicle equipped with a front end loader or grapple.
Although my prior apparatus is a significant improvement over the traditional approach, it has a number of limitations. First, its large size and height require that it be towed to the loading site by a truck. Second, its extensible columns must extend considerably to raise the load of logs sufficiently high load. Third, it does not collapse into a convenient size for storage and transport.
Other log-loading apparatus in the prior art suffer from similar limitations. U.S. Pat. No. 3,764,029 to Riley discloses a log preloader that relies on an extensible column at one end of the loader and a collapsible bunk at the other end for partial elevation of the load. Like my prior apparatus, the columns of the Riley loader are not collapsible. The Riley loader can be carried on a truck bed, but it requires a complex system of jacks and cables to winch the loader on and off the bed.
Another preloading apparatus is disclosed in U.S. Pat. No. 2,919,822 to Darnell. Darnell relies on a cable arrangement for raising a load of logs. The apparatus itself must be lifted by other means onto the bed of a truck to move it between loading sites.
Other patents of interest are U.S. Pat. No. 4,439,098 to Rienks, U.S. Pat. No. 3,578,182 to Harvey, and U.S. Pat. No. 462,312 to Goodyear. None of these patents show log-loading apparatus but instead disclose lumber-handling devices with minor relevance to the art.